K
- the type of keys maintained by this mapV
- the type of mapped valuespublic class FastConcurrentSkipListMap<K,V> extends AbstractMap<K,V> implements ConcurrentNavigableMap<K,V>, Cloneable, Serializable
ConcurrentNavigableMap
implementation. The map
is sorted according to the natural ordering of its keys, or by a Comparator
provided at map creation time, depending on which constructor is used.
This class implements a concurrent variant of SkipLists providing expected average log(n) time cost for the
containsKey, get, put and remove operations and their
variants. Insertion, removal, update, and access operations safely execute concurrently by
multiple threads. Iterators are weakly consistent, returning elements reflecting the
state of the map at some point at or since the creation of the iterator. They do not
throw ConcurrentModificationException
, and may proceed concurrently with other
operations. Ascending key ordered views and their iterators are faster than descending ones.
All Map.Entry pairs returned by methods in this class and its views represent snapshots of mappings at the time they were produced. They do not support the Entry.setValue method. (Note however that it is possible to change mappings in the associated map using put, putIfAbsent, or replace, depending on exactly which effect you need.)
Beware that, unlike in most collections, the size method is not a constant-time operation. Because of the asynchronous nature of these maps, determining the current number of elements requires a traversal of the elements, and so may report inaccurate results if this collection is modified during traversal. Additionally, the bulk operations putAll, equals, toArray, containsValue, and clear are not guaranteed to be performed atomically. For example, an iterator operating concurrently with a putAll operation might view only some of the added elements.
This class and its views and iterators implement all of the optional methods of the
Map
and Iterator
interfaces. Like most other concurrent
collections, this class does not permit the use of null keys or values because
some null return values cannot be reliably distinguished from the absence of elements.
This class is a member of the Java Collections Framework.
AbstractMap.SimpleEntry<K,V>, AbstractMap.SimpleImmutableEntry<K,V>
Constructor and Description |
---|
FastConcurrentSkipListMap()
Constructs a new, empty map, sorted according to the natural ordering
of the keys.
|
FastConcurrentSkipListMap(Comparator<? super K> comparator)
Constructs a new, empty map, sorted according to the specified comparator.
|
FastConcurrentSkipListMap(Map<? extends K,? extends V> m)
Constructs a new map containing the same mappings as the given map, sorted according to the
natural ordering of the keys.
|
FastConcurrentSkipListMap(SortedMap<K,? extends V> m)
Constructs a new map containing the same mappings and using the same ordering as the
specified sorted map.
|
Modifier and Type | Method and Description |
---|---|
Map.Entry<K,V> |
ceilingEntry(K key)
Returns a key-value mapping associated with the least key greater than or equal to the given
key, or null if there is no such entry.
|
K |
ceilingKey(K key) |
void |
clear()
Removes all of the mappings from this map.
|
FastConcurrentSkipListMap<K,V> |
clone()
Returns a shallow copy of this ConcurrentSkipListMap instance.
|
Comparator<? super K> |
comparator() |
boolean |
containsKey(Object key)
Returns true if this map contains a mapping for the specified key.
|
boolean |
containsValue(Object value)
Returns true if this map maps one or more keys to the specified value.
|
NavigableSet<K> |
descendingKeySet() |
ConcurrentNavigableMap<K,V> |
descendingMap() |
Set<Map.Entry<K,V>> |
entrySet()
Returns a
Set view of the mappings contained in this map. |
boolean |
equals(Object o)
Compares the specified object with this map for equality.
|
Map.Entry<K,V> |
firstEntry()
Returns a key-value mapping associated with the least key in this map, or null if
the map is empty.
|
K |
firstKey() |
Map.Entry<K,V> |
floorEntry(K key)
Returns a key-value mapping associated with the greatest key less than or equal to the given
key, or null if there is no such key.
|
K |
floorKey(K key) |
V |
get(Object key)
Returns the value to which the specified key is mapped, or
null if this map contains
no mapping for the key. |
ConcurrentNavigableMap<K,V> |
headMap(K toKey) |
ConcurrentNavigableMap<K,V> |
headMap(K toKey,
boolean inclusive) |
Map.Entry<K,V> |
higherEntry(K key)
Returns a key-value mapping associated with the least key strictly greater than the given
key, or null if there is no such key.
|
K |
higherKey(K key) |
boolean |
isEmpty()
Returns true if this map contains no key-value mappings.
|
NavigableSet<K> |
keySet()
Returns a
NavigableSet view of the keys contained in this map. |
Map.Entry<K,V> |
lastEntry()
Returns a key-value mapping associated with the greatest key in this map, or null if
the map is empty.
|
K |
lastKey() |
Map.Entry<K,V> |
lowerEntry(K key)
Returns a key-value mapping associated with the greatest key strictly less than the given
key, or null if there is no such key.
|
K |
lowerKey(K key) |
NavigableSet<K> |
navigableKeySet() |
Map.Entry<K,V> |
pollFirstEntry()
Removes and returns a key-value mapping associated with the least key in this map, or
null if the map is empty.
|
Map.Entry<K,V> |
pollLastEntry()
Removes and returns a key-value mapping associated with the greatest key in this map, or
null if the map is empty.
|
V |
put(K key,
V value)
Associates the specified value with the specified key in this map.
|
V |
putIfAbsent(K key,
V value) |
V |
remove(Object key)
Removes the mapping for the specified key from this map if present.
|
boolean |
remove(Object key,
Object value) |
V |
replace(K key,
V value) |
boolean |
replace(K key,
V oldValue,
V newValue) |
int |
size()
Returns the number of key-value mappings in this map.
|
ConcurrentNavigableMap<K,V> |
subMap(K fromKey,
boolean fromInclusive,
K toKey,
boolean toInclusive) |
ConcurrentNavigableMap<K,V> |
subMap(K fromKey,
K toKey) |
ConcurrentNavigableMap<K,V> |
tailMap(K fromKey) |
ConcurrentNavigableMap<K,V> |
tailMap(K fromKey,
boolean inclusive) |
Collection<V> |
values()
Returns a
Collection view of the values contained in this map. |
hashCode, putAll, toString
finalize, getClass, notify, notifyAll, wait, wait, wait
compute, computeIfAbsent, computeIfPresent, forEach, getOrDefault, merge, replaceAll
public FastConcurrentSkipListMap()
public FastConcurrentSkipListMap(Comparator<? super K> comparator)
comparator
- the comparator that will be used to order this map. If null, the
natural ordering of the keys will be used.public FastConcurrentSkipListMap(Map<? extends K,? extends V> m)
m
- the map whose mappings are to be placed in this mapClassCastException
- if the keys in m are not Comparable
, or are not
mutually comparableNullPointerException
- if the specified map or any of its keys or values are nullpublic FastConcurrentSkipListMap(SortedMap<K,? extends V> m)
m
- the sorted map whose mappings are to be placed in this map, and whose comparator is
to be used to sort this mapNullPointerException
- if the specified sorted map or any of its keys or values are
nullpublic FastConcurrentSkipListMap<K,V> clone()
clone
in class AbstractMap<K,V>
public boolean containsKey(Object key)
containsKey
in interface Map<K,V>
containsKey
in class AbstractMap<K,V>
key
- key whose presence in this map is to be testedClassCastException
- if the specified key cannot be compared with the keys currently
in the mapNullPointerException
- if the specified key is nullpublic V get(Object key)
null
if this map contains
no mapping for the key.
More formally, if this map contains a mapping from a key k
to a value v
such that key
compares equal to k
according to the map's ordering, then this
method returns v
; otherwise it returns null
. (There can be at most one such
mapping.)
get
in interface Map<K,V>
get
in class AbstractMap<K,V>
ClassCastException
- if the specified key cannot be compared with the keys currently
in the mapNullPointerException
- if the specified key is nullpublic V put(K key, V value)
put
in interface Map<K,V>
put
in class AbstractMap<K,V>
key
- key with which the specified value is to be associatedvalue
- value to be associated with the specified keyClassCastException
- if the specified key cannot be compared with the keys currently
in the mapNullPointerException
- if the specified key or value is nullpublic V remove(Object key)
remove
in interface Map<K,V>
remove
in class AbstractMap<K,V>
key
- key for which mapping should be removedClassCastException
- if the specified key cannot be compared with the keys currently
in the mapNullPointerException
- if the specified key is nullpublic boolean containsValue(Object value)
containsValue
in interface Map<K,V>
containsValue
in class AbstractMap<K,V>
value
- value whose presence in this map is to be testedNullPointerException
- if the specified value is nullpublic int size()
Beware that, unlike in most collections, this method is NOT a constant-time operation. Because of the asynchronous nature of these maps, determining the current number of elements requires traversing them all to count them. Additionally, it is possible for the size to change during execution of this method, in which case the returned result will be inaccurate. Thus, this method is typically not very useful in concurrent applications.
public boolean isEmpty()
public void clear()
public NavigableSet<K> keySet()
NavigableSet
view of the keys contained in this map. The set's iterator
returns the keys in ascending order. The set is backed by the map, so changes to the map are
reflected in the set, and vice-versa. The set supports element removal, which removes the
corresponding mapping from the map, via the Iterator.remove
, Set.remove
,
removeAll
, retainAll
, and clear
operations. It does not support the
add
or addAll
operations.
The view's iterator
is a "weakly consistent" iterator that will never throw ConcurrentModificationException
, and guarantees to traverse elements as they existed upon
construction of the iterator, and may (but is not guaranteed to) reflect any modifications
subsequent to construction.
This method is equivalent to method navigableKeySet
.
public NavigableSet<K> navigableKeySet()
navigableKeySet
in interface ConcurrentNavigableMap<K,V>
navigableKeySet
in interface NavigableMap<K,V>
public Collection<V> values()
Collection
view of the values contained in this map. The collection's
iterator returns the values in ascending order of the corresponding keys. The collection is
backed by the map, so changes to the map are reflected in the collection, and vice-versa. The
collection supports element removal, which removes the corresponding mapping from the map,
via the Iterator.remove, Collection.remove, removeAll,
retainAll and clear operations. It does not support the add or
addAll operations.
The view's iterator is a "weakly consistent" iterator that will never throw
ConcurrentModificationException
, and guarantees to traverse elements as they existed
upon construction of the iterator, and may (but is not guaranteed to) reflect any
modifications subsequent to construction.
public Set<Map.Entry<K,V>> entrySet()
Set
view of the mappings contained in this map. The set's iterator returns
the entries in ascending key order. The set is backed by the map, so changes to the map are
reflected in the set, and vice-versa. The set supports element removal, which removes the
corresponding mapping from the map, via the Iterator.remove, Set.remove,
removeAll, retainAll and clear operations. It does not support
the add or addAll operations.
The view's iterator is a "weakly consistent" iterator that will never throw
ConcurrentModificationException
, and guarantees to traverse elements as they existed
upon construction of the iterator, and may (but is not guaranteed to) reflect any
modifications subsequent to construction.
The Map.Entry elements returned by iterator.next() do not support the setValue operation.
public ConcurrentNavigableMap<K,V> descendingMap()
descendingMap
in interface ConcurrentNavigableMap<K,V>
descendingMap
in interface NavigableMap<K,V>
public NavigableSet<K> descendingKeySet()
descendingKeySet
in interface ConcurrentNavigableMap<K,V>
descendingKeySet
in interface NavigableMap<K,V>
public boolean equals(Object o)
public V putIfAbsent(K key, V value)
putIfAbsent
in interface ConcurrentMap<K,V>
putIfAbsent
in interface Map<K,V>
ClassCastException
- if the specified key cannot be compared with the keys currently
in the mapNullPointerException
- if the specified key or value is nullpublic boolean remove(Object key, Object value)
remove
in interface ConcurrentMap<K,V>
remove
in interface Map<K,V>
ClassCastException
- if the specified key cannot be compared with the keys currently
in the mapNullPointerException
- if the specified key is nullpublic boolean replace(K key, V oldValue, V newValue)
replace
in interface ConcurrentMap<K,V>
replace
in interface Map<K,V>
ClassCastException
- if the specified key cannot be compared with the keys currently
in the mapNullPointerException
- if any of the arguments are nullpublic V replace(K key, V value)
replace
in interface ConcurrentMap<K,V>
replace
in interface Map<K,V>
ClassCastException
- if the specified key cannot be compared with the keys currently
in the mapNullPointerException
- if the specified key or value is nullpublic Comparator<? super K> comparator()
comparator
in interface SortedMap<K,V>
public K firstKey()
firstKey
in interface SortedMap<K,V>
NoSuchElementException
public K lastKey()
lastKey
in interface SortedMap<K,V>
NoSuchElementException
public ConcurrentNavigableMap<K,V> subMap(K fromKey, boolean fromInclusive, K toKey, boolean toInclusive)
subMap
in interface ConcurrentNavigableMap<K,V>
subMap
in interface NavigableMap<K,V>
ClassCastException
NullPointerException
- if fromKey
or toKey
is nullIllegalArgumentException
public ConcurrentNavigableMap<K,V> headMap(K toKey, boolean inclusive)
headMap
in interface ConcurrentNavigableMap<K,V>
headMap
in interface NavigableMap<K,V>
ClassCastException
NullPointerException
- if toKey
is nullIllegalArgumentException
public ConcurrentNavigableMap<K,V> tailMap(K fromKey, boolean inclusive)
tailMap
in interface ConcurrentNavigableMap<K,V>
tailMap
in interface NavigableMap<K,V>
ClassCastException
NullPointerException
- if fromKey
is nullIllegalArgumentException
public ConcurrentNavigableMap<K,V> subMap(K fromKey, K toKey)
subMap
in interface ConcurrentNavigableMap<K,V>
subMap
in interface NavigableMap<K,V>
subMap
in interface SortedMap<K,V>
ClassCastException
NullPointerException
- if fromKey
or toKey
is nullIllegalArgumentException
public ConcurrentNavigableMap<K,V> headMap(K toKey)
headMap
in interface ConcurrentNavigableMap<K,V>
headMap
in interface NavigableMap<K,V>
headMap
in interface SortedMap<K,V>
ClassCastException
NullPointerException
- if toKey
is nullIllegalArgumentException
public ConcurrentNavigableMap<K,V> tailMap(K fromKey)
tailMap
in interface ConcurrentNavigableMap<K,V>
tailMap
in interface NavigableMap<K,V>
tailMap
in interface SortedMap<K,V>
ClassCastException
NullPointerException
- if fromKey
is nullIllegalArgumentException
public Map.Entry<K,V> lowerEntry(K key)
lowerEntry
in interface NavigableMap<K,V>
ClassCastException
NullPointerException
- if the specified key is nullpublic K lowerKey(K key)
lowerKey
in interface NavigableMap<K,V>
ClassCastException
NullPointerException
- if the specified key is nullpublic Map.Entry<K,V> floorEntry(K key)
floorEntry
in interface NavigableMap<K,V>
key
- the keyClassCastException
NullPointerException
- if the specified key is nullpublic K floorKey(K key)
floorKey
in interface NavigableMap<K,V>
key
- the keyClassCastException
NullPointerException
- if the specified key is nullpublic Map.Entry<K,V> ceilingEntry(K key)
ceilingEntry
in interface NavigableMap<K,V>
ClassCastException
NullPointerException
- if the specified key is nullpublic K ceilingKey(K key)
ceilingKey
in interface NavigableMap<K,V>
ClassCastException
NullPointerException
- if the specified key is nullpublic Map.Entry<K,V> higherEntry(K key)
higherEntry
in interface NavigableMap<K,V>
key
- the keyClassCastException
NullPointerException
- if the specified key is nullpublic K higherKey(K key)
higherKey
in interface NavigableMap<K,V>
key
- the keyClassCastException
NullPointerException
- if the specified key is nullpublic Map.Entry<K,V> firstEntry()
firstEntry
in interface NavigableMap<K,V>
public Map.Entry<K,V> lastEntry()
lastEntry
in interface NavigableMap<K,V>
public Map.Entry<K,V> pollFirstEntry()
pollFirstEntry
in interface NavigableMap<K,V>
public Map.Entry<K,V> pollLastEntry()
pollLastEntry
in interface NavigableMap<K,V>
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